U.S. patent application number 11/689201 was filed with the patent office on 2007-09-27 for display device and method of manufacturing the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD. Invention is credited to Hoon KIM, Sang-pil LEE, Un-cheol SUNG.
Application Number | 20070222368 11/689201 |
Document ID | / |
Family ID | 38532652 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070222368 |
Kind Code |
A1 |
LEE; Sang-pil ; et
al. |
September 27, 2007 |
DISPLAY DEVICE AND METHOD OF MANUFACTURING THE SAME
Abstract
An exemplary embodiment of a display device includes a
substrate, a transistor disposed on the substrate, a passivation
layer which substantially covers the transistor, an organic layer
disposed on the passivation layer which generates light to an
outside, and a light efficiency improving layer including a first
inorganic layer and a second inorganic layer which are sequentially
disposed between the organic layer and the outside.
Inventors: |
LEE; Sang-pil; (Seoul,
KR) ; SUNG; Un-cheol; (Anyang-si, KR) ; KIM;
Hoon; (Hwaseong-si, KR) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD
Sunwon-si
KR
|
Family ID: |
38532652 |
Appl. No.: |
11/689201 |
Filed: |
March 21, 2007 |
Current U.S.
Class: |
313/503 ;
313/504; 313/506; 445/24 |
Current CPC
Class: |
H01L 27/3206 20130101;
H01L 27/3211 20130101; H01L 27/3244 20130101; H01L 51/5262
20130101 |
Class at
Publication: |
313/503 ;
313/504; 313/506; 445/24 |
International
Class: |
H05B 33/00 20060101
H05B033/00; H01L 51/50 20060101 H01L051/50; H01L 51/56 20060101
H01L051/56 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2006 |
KR |
10-2006-0025835 |
Claims
1. A display device comprising: a substrate; a transistor disposed
on the substrate; a passivation layer which substantially covers
the transistor; an organic layer disposed on the passivation layer
which generates light to an outside; and a light efficiency
improving layer including a first inorganic layer and a second
inorganic layer which are sequentially disposed between the organic
layer and the outside.
2. The display device according to claim 1, wherein the second
inorganic layer has a higher refractivity than the first inorganic
layer.
3. The display device according to claim 1, wherein the first
inorganic layer and the second inorganic layer contact each
other.
4. The display device according to claim 3, wherein the first
inorganic layer comprises silicon oxide, and the second inorganic
layer comprises silicon nitride.
5. The display device according to claim 4, wherein the thickness
of the first inorganic layer is between about 880 .ANG. and about
1000 .ANG., and the thickness of the second inorganic layer is
between about 600 .ANG. and about 700 .ANG..
6. The display device according to claim 5, further comprising a
pixel electrode disposed between the passivation layer and the
organic layer, wherein the light efficiency improving layer is
disposed between the passivation layer and the pixel electrode.
7. The display device according to claim 5, wherein the passivation
layer comprises an inorganic passivation layer and an organic
passivation layer which is disposed further from the substrate than
the inorganic passivation layer, wherein the light efficiency
improving layer is disposed between the organic passivation layer
and the inorganic passivation layer.
8. The display device according to claim 6, further comprising a
wall disposed on the passivation layer which partitions the pixel
electrodes, and a common electrode which substantially covers the
wall and the organic layer, wherein the light efficiency improving
layer is disposed on the common electrode.
9. The display device according to claim 8, wherein the organic
layer comprises a red organic light emitting layer, a green organic
light emitting layer and a blue organic light emitting layer, and
the light efficiency improving layer comprises a plurality of
sections corresponding to the red, green and blue organic light
emitting layers, respectively, and at least one of the plurality of
sections has a thickness which differs from the other sections.
10. The display device according to claim 8, wherein the organic
layer comprises a red organic light emitting layer, a green organic
light emitting layer and a blue organic light emitting layer, the
light efficiency improving layer comprises a plurality of sections
corresponding to the red, green and blue organic light emitting
layers, respectively, and at least one of the plurality of sections
covers a different sized area.
11. The display device according to claim 8, wherein at least one
of the first inorganic layer and the second inorganic layer
comprises multiple layers.
12. The display device according to claim 7, wherein the organic
layer comprises a red organic light emitting layer, a green organic
light emitting layer and a blue organic light emitting layer, and
the light efficiency improving layer comprises a plurality of
sections corresponding to the red, green and blue organic light
emitting layers, respectively, and at least one of the plurality of
sections has a thickness which differs from the other sections.
13. The display device according to claim 7, wherein the organic
layer comprises a red organic light emitting layer, a green organic
light emitting layer and a blue organic light emitting layer, and
the light efficiency improving layer comprises a plurality of
sections corresponding to the red, green and blue organic light
emitting layers, respectively, and at least one of the plurality of
sections covers a different sized area.
14. The display device according to claim 7, wherein at least one
of the first inorganic layer and the second inorganic layer
comprises multiple layers.
15. The display device according to claim 6, wherein the organic
layer comprises a red organic light emitting layer, a green organic
light emitting layer and a blue organic light emitting layer, and
the light efficiency improving layer comprises a plurality of
sections corresponding to the red, green and blue organic light
emitting layers, respectively, and at least one of the plurality of
sections has a thickness which differs from the other sections.
16. The display device according to claim 6, wherein the organic
layer comprises a red organic light emitting layer, a green organic
light emitting layer and a blue organic light emitting layer, and
at least one portion of the light efficiency improving layer
comprises a plurality of sections corresponding to the red, green
and blue organic light emitting layers, respectively, and at least
one of the plurality of sections covers a different sized area.
17. The display device according to claim 6, wherein at least one
of the first inorganic layer and the second inorganic layer
comprises multiple layers.
18. A display device comprising: a transistor disposed on a
substrate; an inorganic passivation layer which substantially
covers the transistor; a color filter layer disposed on the
inorganic passivation layer; an organic passivation layer which
substantially covers the color filter layer; a light efficiency
improving layer which includes a first inorganic layer and a second
inorganic layer which are sequentially disposed on the organic
passivation layer; and a pixel electrode and an organic layer which
are sequentially disposed on the light efficiency improving
layer.
19. The display device according to claim 18, wherein the second
inorganic layer has a higher refractivity than the first inorganic
layer.
20. The display device according to claim 18, wherein at least one
of the first inorganic layer and the second inorganic layer
comprises multiple layers.
21. The display device according to claim 18, wherein the first
inorganic layer and the second inorganic layer contact each other,
and the first inorganic layer comprises silicon oxide and the
second inorganic layer comprises silicon nitride.
22. The display device according to claim 21, wherein the thickness
of the first inorganic layer is between about 880 .ANG. and about
1000 .ANG., and the thickness of the second inorganic layer is
between about 600 .ANG. and about 700 .ANG..
23. The display device according to claim 22, wherein the organic
layer emits white light.
24. The display device according to claim 22, wherein the color
filter layer comprises a red color filter layer, a green color
filter layer and a blue color filter layer, and at least one
portion of the light efficiency improving layer comprises a
plurality of sections corresponding to the red, green and blue
organic light emitting layers, respectively, and at least one of
the plurality of sections has a thickness which differs from the
other sections.
25. The display device according to claim 22, wherein the color
filter layer comprises a red color filter layer, a green color
filter layer and a blue color filter layer, and at least one
portion of the light efficiency improving layer comprises a
plurality of sections corresponding to the red, green and blue
organic light emitting layers, respectively, and at least one of
the plurality of sections covers a different sized area.
26. A display device comprising: a transistor disposed on a
substrate; a passivation layer which substantially covers the
transistor; a pixel electrode formed on the passivation layer; a
wall which divides the pixel electrodes; an organic layer formed on
the pixel electrode between the walls; a common electrode which
substantially covers the organic layer and the wall; a light
efficiency improving layer including a first inorganic layer and a
second inorganic layer which are sequentially disposed on the
common electrode between the walls; and a color filter layer
disposed on the light efficiency improving layer.
27. The display device according to claim 26 wherein the second
inorganic layer has a higher refractivity than the first inorganic
layer.
28. The display device according to claim 26, wherein at least one
of the first inorganic layer and the second inorganic layer
comprises multiple layers.
29. A method of manufacturing a display device, the method
comprising: sequentially disposing a plurality of transistors and a
passivation layer on a substrate, the passivation layer
substantially covering the transistors; sequentially disposing a
first inorganic layer and a second inorganic layer on the
passivation layer; patterning the first inorganic layer and the
second inorganic layer to be disposed between the transistors;
disposing a pixel electrode on the first and second inorganic
layer; disposing an organic layer on the pixel electrode; and
disposing a common electrode on the organic layer.
30. The method of manufacturing a display device according to claim
29, wherein the second inorganic layer is formed to have a higher
refractivity than the first inorganic layer.
31. The method of manufacturing a display device according to claim
29, wherein the first inorganic layer and the second inorganic
layer are patterned at substantially the same time.
32. The method of manufacturing a display device according to claim
31, wherein the first inorganic layer comprises silicon oxide, and
the second inorganic layer comprises silicon nitride, and the
thickness of the first inorganic layer is between about 880 .ANG.
and about 1000 .ANG., and the thickness of the second inorganic
layer is between about 600 .ANG. and about 700 .ANG..
33. The method of manufacturing according to claim 32, further
comprising disposing a color filter layer which at least partially
overlaps with the organic layer between the transistors and the
passivation layer.
34. The method of manufacturing according to claim 33, wherein the
organic layer emits white light.
Description
[0001] This application claims priority to Korean Patent
Application No. 2006-0025835, filed on Mar. 21, 2006, and all the
benefits accruing therefrom under 35 U.S.C. .sctn.119, the contents
of which in its entirety are herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a display device and a
method of manufacturing the same, and more particularly, to a
display device having improved light efficiency and color purity
and a method of manufacturing the same.
[0004] 2. Description of the Related Art
[0005] Recently, organic light emitting diode ("OLED") display
devices have attracted attention and interest in the industry of
flat panel display devices because of their low-power requirements,
light weight, slim shape, wide viewing angle, high-speed response
and other positive attributes.
[0006] An OLED display includes an insulating substrate, a thin
film transistor ("TFT") provided on the insulating substrate, a
pixel electrode connected to the TFT, a wall partitioning the pixel
electrodes, an organic layer formed on the pixel electrode between
the walls, and a common electrode formed on the wall and the
organic layer.
[0007] The TFT controls the emission of light from a light emitting
layer in each individual pixel region. A pixel electrode is
disposed in each pixel region to form an individual pixel. Each
pixel electrode is electrically isolated from its neighboring pixel
electrodes so it may be driven independently from surrounding pixel
electrodes. The wall between the neighboring pixel regions is
formed to be higher than the pixel electrodes. The wall prevents
short-circuits between the pixel electrodes and isolates each pixel
region. An organic layer including a hole injecting layer and a
light emitting layer is formed on the pixel electrode between the
walls. The OLED display device with the aforementioned
configuration displays images by controlling light generated from
the light emitting layer in each pixel region.
[0008] The light generated from the light emitting layer passes
through a plurality of layers to be emitted outside of the OLED
display device. However, while passing through the plurality of
layers the light is scattered as each layer has a different degree
of refractivity, thereby deteriorating light efficiency and color
purity of the emitted light. One method of overcoming this
deterioration is to emit light with a high degree of brightness.
However, power consumption increases and the light emitting layer
deteriorates more rapidly when a light with a high degree of
brightness is emitted.
BRIEF SUMMARY OF THE INVENTION
[0009] Accordingly, it is an aspect of the present invention to
provide a display device having improved light efficiency and color
purity.
[0010] Another aspect of the present invention is to provide a
method of manufacturing a display device having improved light
efficiency and color purity.
[0011] An exemplary embodiment of a display device includes; a
substrate, a transistor disposed on the substrate, a passivation
layer which substantially covers the transistor, an organic layer
disposed on the passivation layer which generates light to an
outside, and a light efficiency improving layer including a first
inorganic layer and a second inorganic layer which are sequentially
disposed between the organic layer and the outside.
[0012] According to an exemplary embodiment of the present
invention the second inorganic layer has a higher refractivity than
the first inorganic layer.
[0013] According to an exemplary embodiment of the present
invention the first inorganic layer and the second inorganic layer
contact each other.
[0014] According to an exemplary embodiment of the present
invention, the first inorganic layer includes silicon oxide
("SiOx"), and the second inorganic layer comprises silicon nitride
("SiNx").
[0015] According to an exemplary embodiment of the present
invention, the thickness of the first inorganic layer is between
about 880 .ANG. and about 1000 .ANG., and the thickness of the
second inorganic layer is between about 600 .ANG. and about 700
.ANG..
[0016] According to an exemplary embodiment of the present
invention, the display device further includes a pixel electrode
disposed between the passivation layer and the organic layer,
wherein the light efficiency improving layer is disposed between
the passivation layer and the pixel electrode.
[0017] According to an exemplary embodiment of the present
invention, the passivation layer comprises an inorganic passivation
layer and an organic passivation layer which is disposed further
from the substrate than the inorganic passivation layer, wherein
the light efficiency improving layer is disposed between the
organic passivation layer and the inorganic passivation layer.
[0018] According to an exemplary embodiment of the present
invention, the display device further includes a wall disposed on
the passivation layer which partitions the pixel electrodes, and a
common electrode which substantially covers the wall and the
organic layer, wherein the light efficiency improving layer is
disposed on the common electrode.
[0019] According to an exemplary embodiment of the present
invention, the organic layer includes a red organic light emitting
layer, a green organic light emitting layer and a blue organic
light emitting layer, and the light efficiency improving layer
includes a plurality of sections corresponding to the red, green
and blue organic light emitting layers, respectively, and at least
one of the plurality of sections has a thickness which differs from
the other sections.
[0020] According to an exemplary embodiment of the present
invention, the organic layer includes a red organic light emitting
layer, a green organic light emitting layer and a blue organic
light emitting layer, the light efficiency improving layer includes
a plurality of sections corresponding to the red, green and blue
organic light emitting layers, respectively, and at least one of
the plurality of sections covers a different sizes area.
[0021] An exemplary embodiment of a display device includes; a
transistor disposed on a substrate, an inorganic passivation layer
which substantially covers the transistor, a color filter layer
disposed on the inorganic passivation layer, an organic passivation
layer which substantially covers the color filter layer, a light
efficiency improving layer which includes a first inorganic layer
and a second inorganic layer which are sequentially disposed on the
organic passivation layer, and a pixel electrode and an organic
layer which are sequentially disposed on the light efficiency
improving layer.
[0022] According to an exemplary embodiment of the present
invention, the second inorganic layer has a higher refractivity
than the first inorganic layer.
[0023] According to an exemplary embodiment of the present
invention, the first inorganic layer and the second inorganic layer
contact each other, and the first inorganic layer includes silicon
oxide ("SiOx") and the second inorganic layer includes silicon
nitride ("SiNx").
[0024] According to an exemplary embodiment of the present
invention, the thickness of the first inorganic layer is between
about 880 .ANG. and about 1000 .ANG., and the thickness of the
second inorganic layer is between about 600 .ANG. and about 700
.ANG..
[0025] According to an exemplary embodiment of the present
invention, the organic layer emits white light.
[0026] According to an exemplary embodiment of the present
invention, the color filter layer includes a red color filter
layer, a green color filter layer and a blue color filter layer,
and at least one portion of the light efficiency improving layer
includes a plurality of sections corresponding to the red, green
and blue organic light emitting layers, respectively, and at least
one of the plurality of sections has a thickness which differs from
the other sections.
[0027] According to an exemplary embodiment of the present
invention, the color filter layer includes a red color filter
layer, a green color filter layer and a blue color filter layer,
and at least one portion of the light efficiency improving layer
includes a plurality of sections corresponding to the red, green
and blue organic light emitting layers, respectively, and at least
one of the plurality of sections covers a different sized area.
[0028] An exemplary embodiment of a display device includes; a
transistor disposed on an insulating substrate, a passivation layer
which substantially covers the transistor, a pixel electrode
disposed on the passivation layer, a wall which divides the pixel
electrodes, an organic layer disposed on the pixel electrode
between the walls, a common electrode which substantially covers
the organic layer and the wall, a light efficiency improving layer
including a first inorganic layer and a second inorganic layer
which are sequentially disposed on the common electrode between the
walls, and a color filter layer disposed on the light efficiency
improving layer.
[0029] According to an exemplary embodiment of the present
invention, the second inorganic layer has a higher refractivity
than the first inorganic layer.
[0030] According to an exemplary embodiment of the present
invention, at least one of the first inorganic layer and the second
inorganic layer includes multiple layers.
[0031] An exemplary embodiment of a method of manufacturing a
display device includes sequentially disposing a plurality of
transistors and a passivation layer on a substrate, the passivation
layer substantially covering the transistors, sequentially
disposing a first inorganic layer and a second inorganic layer on
the passivation layer, patterning the first inorganic layer and the
second inorganic layer to be disposed between the transistors,
disposing a pixel electrode on the first and second inorganic
layer, disposing an organic layer on the pixel electrode, and
disposing a common electrode on the organic layer.
[0032] According to an exemplary embodiment of the present
invention, the second inorganic layer is formed to have a higher
refractivity than the first inorganic layer.
[0033] According to an exemplary embodiment of the present
invention, the first inorganic layer and the second inorganic layer
are patterned at substantially the same time.
[0034] According to an exemplary embodiment of the present
invention, the first inorganic layer includes silicon oxide
("SiOx"), and the second inorganic layer includes silicon nitride
("SiNx"), and the thickness of the first inorganic layer is between
about 880 .ANG. and about 1000 .ANG., and the thickness of the
second inorganic layer is between about 600 .ANG. and about 700
.ANG..
[0035] According to an exemplary embodiment of the present
invention, the method of manufacturing further includes disposing a
color filter layer which at least partially overlaps with the
organic layer between the transistors and the passivation
layer.
[0036] According to an exemplary embodiment of the present
invention, the organic layer emits white light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The above and/or other aspects and advantages of the present
invention will become more readily apparent and appreciated in
light of the following description of the exemplary embodiments,
taken in conjunction with the accompanying drawings of which:
[0038] FIG. 1 is an equivalent circuit diagram of a first exemplary
embodiment of a display device according to the present
invention;
[0039] FIG. 2 is a cross-sectional view of the first exemplary
embodiment of a display device according to the present
invention;
[0040] FIGS. 3A through 3E illustrate an exemplary embodiment of a
method of manufacturing the display device according to the present
invention; and
[0041] FIGS. 4 through 8 are cross-sectional views of second
through sixth exemplary embodiments of a display device according
to the present invention, respectively.
DETAILED DESCRIPTION OF THE INVENTION
[0042] The invention now will be described more fully hereinafter
with reference to the accompanying drawings, in which embodiments
of the invention are shown. This invention may, however, be
embodied in many different forms and should not be construed as
limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this disclosure will be thorough
and complete, and will fully convey the scope of the invention to
those skilled in the art. Like reference numerals refer to like
elements throughout.
[0043] It will be understood that when an element is referred to as
being "on" another element, it can be directly on the other element
or intervening elements may be present therebetween. In contrast,
when an element is referred to as being "directly on" another
element, there are no intervening elements present. As used herein,
the term "and/or" includes any and all combinations of one or more
of the associated listed items.
[0044] It will be understood that, although the terms first,
second, third etc. may be used herein to describe various elements,
components, regions, layers and/or sections, these elements,
components, regions, layers and/or sections should not be limited
by these terms. These terms are only used to distinguish one
element, component, region, layer or section from another region,
layer or section. Thus, a first element, component, region, layer
or section discussed below could be termed a second element,
component, region, layer or section without departing from the
teachings of the present invention.
[0045] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," or "includes"
and/or "including" when used in this specification, specify the
presence of stated features, regions, integers, steps, operations,
elements, and/or components, but do not preclude the presence or
addition of one or more other features, regions, integers, steps,
operations, elements, components, and/or groups thereof.
[0046] Furthermore, relative terms, such as "lower" or "bottom" and
"upper" or "top," may be used herein to describe one element's
relationship to another elements as illustrated in the Figures. It
will be understood that relative terms are intended to encompass
different orientations of the device in addition to the orientation
depicted in the Figures. For example, if the device in one of the
figures is turned over, elements described as being on the "lower"
side of other elements would then be oriented on "upper" sides of
the other elements. The exemplary term "lower", can therefore,
encompasses both an orientation of "lower" and "upper," depending
of the particular orientation of the figure. Similarly, if the
device in one of the figures is turned over, elements described as
"below" or "beneath" other elements would then be oriented "above"
the other elements. The exemplary terms "below" or "beneath" can,
therefore, encompass both an orientation of above and below.
[0047] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning which is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0048] Embodiments of the present invention are described herein
with reference to cross section illustrations which are schematic
illustrations of idealized embodiments of the present invention. As
such, variations from the shapes of the illustrations as a result,
for example, of manufacturing techniques and/or tolerances, are to
be expected. Thus, embodiments of the present invention should not
be construed as limited to the particular shapes of regions
illustrated herein but are to include deviations in shapes which
result, for example, from manufacturing. For example, a region
illustrated or described as flat may, typically, have rough and/or
nonlinear features. Moreover, sharp angles which are illustrated
may be rounded. Thus, the regions illustrated in the figures are
schematic in nature and their shapes are not intended to illustrate
the precise shape of a region and are not intended to limit the
scope of the present invention.
[0049] Hereinafter, the present invention will be described in
detail with reference to the accompanying drawings.
[0050] FIG. 1 is an equivalent circuit diagram of a first exemplary
embodiment of a display device according to the present
invention.
[0051] Referring to FIG. 1, one exemplary embodiment of a pixel in
the first exemplary embodiment of a display device according to the
present invention comprises a plurality of signal lines. The signal
lines comprise a gate line transmitting a scanning signal, a data
line transmitting a data signal and a voltage supply line
transmitting a driving voltage. The data line and the voltage
supply line are disposed substantially adjacently and substantially
parallel to each other. The gate line extends substantially
perpendicularly to the data line and the voltage supply line.
[0052] Each pixel comprises an organic light emitting element LD, a
switching thin film transistor Tsw, a driving thin film transistor
Tdr and a capacitor C.
[0053] The driving thin film transistor Tdr comprises a control
terminal, an input terminal and an output terminal. The control
terminal is connected to the switching thin film transistor Tsw,
the input terminal is connected to the voltage supply line, and the
output terminal is connected to the organic light emitting element
LD.
[0054] The organic light emitting element LD comprises an anode
connected to the output terminal of the driving thin film
transistor Tdr and a cathode connected to a common voltage Vcom.
The organic light emitting element LD emits light with a variable
intensity depending on an output current from the driving thin film
transistor Tdr applied thereto. A plurality of light emitting
elements may be used together to display images. The intensity of
the current from the driving thin film transistor Tdr varies
depending on a voltage between the control terminal and the output
terminal thereof.
[0055] The switching thin film transistor Tsw comprises a control
terminal, an input terminal and an output terminal. The control
terminal is connected to the gate line, the input terminal is
connected to the data line, and the output terminal is connected to
the control terminal of the driving thin film transistor Tdr. The
switching thin film transistor Tsw transmits the data signal
applied to the data line to the driving thin film transistor Tdr in
response to the scanning signal applied to the gate line.
[0056] The capacitor C is connected between the control terminal of
the driving thin film transistor Tdr and the input terminal
thereof. The capacitor C is charged with a voltage corresponding to
the data signal input to the control terminal of the driving thin
film transistor Tdr and maintains the voltage during a light
emitting time period.
[0057] To display moving images the display device rapidly displays
a series of slightly changing images. The rapid display of these
slightly varying images creates an illusion of movement. Each image
is displayed for a short time period also referred to as a frame.
In one exemplary embodiment the light emitting time period during
which the capacitor maintains the voltage corresponding to the data
signal may be one frame.
[0058] Referring to FIG. 2, a cross-sectional view of the first
exemplary embodiment of a display device according to the present
invention will be described in detail. FIG. 2 shows only the
driving thin film transistor Tdr without the switching thin film
transistor Tsw.
[0059] A gate electrode 121 is formed on an insulating substrate
110, exemplary embodiments of which are made of glass, quartz,
ceramic or plastic. A gate insulating layer 131, one exemplary
embodiment of which is made of silicon nitride ("SiNx"), is formed
on the insulating substrate 110 and the gate electrode 121.
[0060] A semiconductor layer 132 and an ohmic contact layer 133 are
sequentially formed on the gate insulating layer 131 substantially
above the gate electrode. In one exemplary embodiment the
semiconductor layer 132 is made of amorphous silicon, and the ohmic
contact layer 133 is made of n+ hydrogenated amorphous silicon
which is highly doped with n-type impurities. The ohmic contact
layer 133 is divided into two parts, the gate electrode 121 being
disposed therebetween.
[0061] A source electrode 141 and a drain electrode 142 are formed
on the ohmic contact layer 133 and the gate insulating layer 131.
The source electrode 141 and the drain electrode 142 are separated
from each other, the gate electrode 121 being disposed
therebetween.
[0062] A passivation layer 150 is formed on the source electrode
141, the drain electrode 142 and the portion of the semiconductor
layer 132 which is exposed between the source and drain electrodes
141 and 142. In one exemplary embodiment the passivation layer 150
may comprise an inorganic passivation layer 151 made of silicon
nitride ("SiNx") and an organic passivation layer 153. In such an
exemplary embodiment the organic material for the organic
passivation layer 153 may include one of benzocyclobutene ("BCB"),
olefin, acrylic resin, polyimde, Teflon.TM., Cytop.TM. and
perfluorocyclobutene ("FCB"). In one exemplary embodiment a surface
of the organic passivation layer 153 is substantially flat, a
contact hole 155 is formed in the inorganic passivation layer 151
and the organic passivation layer 153 to expose a portion of the
drain electrode 142.
[0063] A light efficiency improving layer 160 is formed on the
organic passivation layer 153. In one exemplary embodiment the
light efficiency improving layer 160 comprises a first inorganic
layer 161 in the lower part thereof and a second inorganic layer
163 in the upper part thereof. The second inorganic layer 163 has a
higher refractivity than the first inorganic layer 161 and contacts
the first inorganic layer 161. In one exemplary embodiment the
first inorganic layer 161 includes silicon oxide ("SiOx") and the
second inorganic layer 163 includes silicon nitride ("SiNx"). The
two inorganic layers 161 and 163 are substantially transparent.
[0064] In one exemplary embodiment the thickness of the first
inorganic layer 161 may be between about 880 .ANG. and about 1000
.ANG., and the thickness of the second inorganic layer 163 may be
between about 600 .ANG. and about 700 .ANG.. The wavelength of
light generated in an organic light emitting layer 192 is modified
by the light efficiency improving layer 160, thereby improving
light efficiency and color purity. The wavelength of the light may
be desirably adjusted depending on the refractivities and
thicknesses of the first and second inorganic layers 161 and
163.
[0065] In one exemplary embodiment the organic light emitting layer
192 comprises a plurality of differently colored light emitting
layers 192 in different pixel regions. One exemplary embodiment of
the different colors includes red, green and blue light emitting
layers, each different colored light emitting layer disposed in a
separate pixel region. In such an exemplary embodiment pixel
regions including light emitting layers 192 emitting light of
differing colors are disposed substantially adjacently to one
another.
[0066] In another exemplary embodiment to be discussed below with
reference to FIGS. 6 and 7 the light emitting layer 192 emits white
light, either by including a white light emitting organic light
emitting layer or by including a combination of red, green, and
blue light emitting layers within a single pixel region. In such an
exemplary embodiment the addition of a color filter becomes
necessary in order to display colors. While a few exemplary
embodiments of the light emitting layer have been disclosed above,
the present invention is not limited thereto, but may include
various alternative configurations.
[0067] The light efficiency improving layer 160 may be formed with
a different thickness depending on which color light emitting layer
192 it is disposed to overlap. In the exemplary embodiment wherein
the organic light emitting layer 192 comprises a red organic light
emitting layer, a green organic light emitting layer and a blue
organic light emitting layer at least one portion of the light
efficiency improving layer 160 corresponding to the red, green and
blue organic light emitting layers 192 may have a different
thickness. For example, the three light efficiency improving layers
160 corresponding to the three colors may have three different
thicknesses, or only one portion of the light efficiency improving
layer 160 may have a different thickness from those of the other
two portions.
[0068] Likewise, at least one portion of the light efficiency
improving layer 160 corresponding to the red, green and blue
organic light emitting layers 192 may cover a different sized
area.
[0069] The light efficiency improving layer 160 modulated with the
aforementioned exemplary configuration produces uniform light
efficiency and/or color purity with respect to the different light
emitting efficiency and color purity depending on the red, green
and blue organic light emitting layers.
[0070] However, the light efficiency improving layer 160 may also
deteriorate the light efficiency and the color purity of the light
emitting layer 192 depending on the characteristics of the light
emitting layer 192. In this case, a portion of the light efficiency
improving layer 160 may be removed corresponding to the organic
light emitting layer 192 where the light efficiency and the color
purity has been lowered.
[0071] In one exemplary embodiment the area of the light efficiency
improving layer 160 is substantially the same as or larger than the
area of the light emitting layer 192.
[0072] A pixel electrode 170 is formed on the light efficiency
improving layer 160. The pixel electrode 160 is referred to as an
anode and provides holes to an organic layer 190. In one exemplary
embodiment the pixel electrode 170 is made of a transparent
conductive material such as indium tin oxide ("ITO") or indium zinc
oxide ("IZO") and is connected to the drain electrode 142 through a
contact hole 155.
[0073] A wall 180 is formed on the pixel electrode 170 and an
organic passivation layer 153 which surrounds the pixel electrode
170 underneath the light emitting layer 192. The wall 180
partitions the pixel electrodes 170 to define a pixel region. The
wall 180 provides additional space between the electrodes of the
driving transistor, namely the source electrode 141 and the drain
electrode 142 and a common electrode 200, which prevents short
circuiting therebetween. In one exemplary embodiment the wall 180
is made of a photoresist material with thermal resistance and
solvent resistance characteristics, exemplary embodiments of which
include acrylic resin, polyimide resin, and various other similar
materials; an inorganic material exemplary embodiments of which
include SiO2 and TiO2; or double layers of an organic layer and an
inorganic layer.
[0074] An organic layer 190 is formed on a portion of the pixel
electrode 170 left uncovered by the formation of the wall 180. In
one exemplary embodiment the organic layer 190 comprises a hole
injecting layer 191 and the organic light emitting layer 192.
Alternative exemplary embodiments include configurations wherein
the organic layer 190 includes additional layers such as a hole
transport layer (not shown), an electron injection layer (not
shown), an electron transport layer (not shown), or various
combinations of the above. Alternative exemplary embodiments also
include configurations wherein only a light emitting layer is
included.
[0075] The hole injecting layer 191 may include a hole injecting
material exemplary embodiments of which include
poly-3,4-ethylenedioxythiophene ("PEDOT"), poly styrenesulfonate
acid ("PSS") or other similar materials and may be formed by
ink-jetting the hole injecting material in an aqueous suspension
state.
[0076] The organic light emitting layer 192 comprises the red
organic light emitting layer, the green organic light emitting
layer and the blue organic light emitting layer. Exemplary
embodiments of the organic light emitting layer 192 may include
polyfluorene derivatives, poly(p-paraphenylene vinylene)
derivatives, polyphenylene derivatives, poly(vinylcarbazole)
derivatives and poly thiophene derivatives; or compounds thereof
doped with a perillene group pigment, rhodamine group pigment,
rubrene, perillene, 9,10-diphenylanthracene, tetraphenylbutadiene,
Nile red, cumarine 6, quinacridone, or other similar materials.
[0077] Holes provided from the pixel electrode 170 and electrons
provided from the common electrode 200 are combined in the organic
light emitting layer 192 to form excitons. The excitons generate
light through their deactivation process.
[0078] The common electrode 200 is formed on the wall 180 and the
organic light emitting layer 192. The common electrode 200 is
referred to as a cathode and provides electrons to the organic
light emitting layer 192. The common electrode 200 is made of an
opaque material exemplary embodiments of which include aluminum,
silver or other similar materials. Light emitted from the organic
light emitting layer 192 exits toward the insulating substrate
110.
[0079] The display device described above is a bottom-emission type
display wherein light from the organic light emitting layer 192
exits toward the insulating substrate 110. However, the display
device may be a top-emission type display wherein the light from
the organic light emitting layer 192 exits through the common
electrode 200.
[0080] Hereinafter, an exemplary embodiment of a method of
manufacturing the first exemplary embodiment of a display device
according to the present invention will be described with reference
FIGS. 3A through 3E.
[0081] Referring to FIG. 3A, the driving TFT Tdr, the inorganic
passivation layer 151 covering the TFT and the organic passivation
layer 153 are formed on the insulating substrate 110. The driving
TFT Tdr is formed by any of several well known methods, and the
inorganic passivation layer 151 is formed on the driving TFT Tdr.
In one exemplary embodiment the inorganic passivation layer 151 is
formed by chemical vapor deposition of silicon nitride. The organic
passivation layer 153 is formed by spin coating, slit coating,
screen printing, or other similar techniques.
[0082] Referring to FIG. 3B, the first inorganic layer 161,
exemplary embodiments of which include silicon oxide, and the
second inorganic layer 163, exemplary embodiments of which include
silicon nitride, are sequentially formed on the surface of the
organic passivation layer 153. In one exemplary embodiment they may
be formed by chemical vapor deposition. In the present exemplary
embodiment, other elements do not intervene between the first
inorganic layer 161 and the second inorganic layer 163, and the
second inorganic layer 163 has a higher refractivity than the first
inorganic layer 161. According to the present exemplary embodiment
the thickness of the first inorganic layer 161 may be between about
880 .ANG. and about 1000 .ANG., and the thickness of the second
inorganic layer 163 may be between about 600 .ANG. and about 700
.ANG..
[0083] Referring to FIG. 3C, the first inorganic layer 161 and the
second inorganic layer 163 are patterned to correspond to a display
region, thereby forming the light efficiency improving layer 160.
In the present exemplary embodiment the patterning may be performed
by photolithography. The light efficiency improving layer 160 may
be formed into a plurality of sections to correspond to the organic
layer 190 between the walls 180. In the present exemplary
embodiment, the first inorganic layer 161 and the second inorganic
layer 163 are patterned at the same time.
[0084] The light efficiency improving layer 160 may be formed with
different thicknesses depending on its location. The organic light
emitting layer 192 comprises a red organic light emitting layer, a
green organic light emitting layer and a blue organic light
emitting layer, and at least one section of the light efficiency
improving layer 160 corresponding to the red, green and blue
organic light emitting layers 192 may have a different thickness.
For example, the three sections of the light efficiency improving
layer 160 corresponding to the three colors may have three
different thicknesses, or only one portion of the light efficiency
improving layer 160 may have a different thickness from those of
the other two portions.
[0085] Likewise, at least one portion of the light efficiency
improving layer 160 among the three sections corresponding to the
red, green and blue organic light emitting layers 192 may cover a
different sized area.
[0086] The light efficiency improving layer 160 with the
aforementioned configuration achieves more uniform light emitting
efficiency and/or color purity throughout the entire display as the
light emitting efficiency and the color purity may vary depending
on the red, green and blue organic light emitting layers.
[0087] However, the light efficiency improving layer 160 may also
deteriorate the light efficiency and the color purity of the light
emitting layer 192 depending on the characteristics of the light
emitting layer 192. In this case, a portion of the light efficiency
improving layer 160 may be removed corresponding to a portion of
the organic light emitting layer 192 where the light efficiency and
the color purity have been lowered.
[0088] In another exemplary embodiment the area of the light
efficiency improving layer 160 is substantially the same as or
larger than the area of the light emitting layer 192.
[0089] Referring to FIG. 3D, the contact hole 155 is formed in the
inorganic passivation layer 151 and the organic passivation layer
153 to expose a portion of the drain electrode 142. The contact
hole 155 may be formed by any of several well-known methods.
[0090] Referring to FIG. 3E, the pixel electrode 170 and the wall
180 are formed by any of several well-known methods. The pixel
electrode 170 contacts the drain electrode 142 through the contact
hole 155 and substantially covers the light efficiency improving
layer 160. The wall 180 partitions the pixel electrodes 170 to
define the pixel region.
[0091] The organic layer 190 and the common electrode 200 are
formed by any of several well-known methods, thereby completing the
exemplary embodiment of an OLED display shown in FIG. 2.
[0092] Hereinafter, second through sixth exemplary embodiments of a
display device according to the present invention will be described
with reference to FIGS. 4 through 8. It should be noted that the
following description will be made with particular emphasis given
to the features which differentiate the second through sixth
exemplary embodiments from those of the first exemplary
embodiment.
[0093] FIG. 4 is a cross-sectional view of second exemplary
embodiment of an OLED display according to the present invention.
The second exemplary embodiment of an OLED display is
bottom-emission type display as has been described above. A light
efficiency improving layer 160 is disposed between an organic
passivation layer 153 and an inorganic passivation layer 151. In
such an exemplary embodiment, a first inorganic layer 161 and a
second inorganic layer 163 of the light efficiency improving layer
160 are sequentially formed after the inorganic passivation layer
151 covering a driving TFT Tdr is formed. Then, the first inorganic
layer 161 and the second inorganic layer 163 are patterned to
correspond to an organic layer 190, thereby completing the light
efficiency improving layer 160. The organic passivation layer 153
is formed to cover the inorganic passivation layer 151 and the
light efficiency improving layer 160. A contact hole 155 is formed
in the inorganic passivation layer 151 and the organic passivation
layer 153 to expose a portion of a drain electrode 142. In another
exemplary embodiment the light efficiency improving layer 160 may
be also formed between a gate insulating layer 131 and the
inorganic passivation layer 151.
[0094] FIG. 5 is a cross-sectional view of a third exemplary
embodiment of an OLED display according to the present invention.
The third exemplary embodiment of an OLED is top-emission type
display as has been described above. A light efficiency improving
layer 160 may be disposed on a common electrode 200 between walls
180. In such an exemplary embodiment, a pixel electrode 170 may be
made of an opaque material, although alternative exemplary
embodiments include configurations wherein the pixel electrode 170
is made of a transparent material, and the common electrode 200 is
made of a transparent material.
[0095] FIG. 6 is a cross-sectional view of a fourth exemplary
embodiment of an OLED display according to the present invention.
The fourth exemplary embodiment of an OLED display is
bottom-emission type display as has been described above. A light
efficiency improving layer 160 is disposed between an organic
passivation layer 153 and a pixel electrode 170, similar to the
first exemplary embodiment. In the fourth exemplary embodiment,
however, an organic light emitting layer 192 in the OLED emits
white light. Therefore, in order to produce a color display, a
color filter layer 210 is disposed between an inorganic passivation
layer 151 and the organic passivation layer 153. In such an
exemplary embodiment the color filter layer 210 at least partially
overlaps an organic layer 190. The unwanted colors are filtered
from the white light generated from the organic light emitting
layer 192 while the light passes through the color filter layer
210.
[0096] In the fourth exemplary embodiment, the organic light
emitting layer 192 includes a polymer. In one exemplary embodiment,
the organic light emitting layer 192 is formed between walls 180 by
ink-jetting. However, alternative exemplary embodiments include
configurations wherein the organic light emitting layer 192
includes a low molecular weight material, and in such an exemplary
embodiment the light emitting layer 192 is formed on substantially
the entire surface of an insulating substrate 110 by a method such
as evaporation.
[0097] The color filter layer 210 comprises a red color filter
layer, a green color filter layer and a blue color filter layer.
The light efficiency improving layer 160 may be divided into
different sections corresponding to the red, green and blue color
filters 210. Each of the different sections may have a different
thickness. Furthermore, in one exemplary embodiment, at least one
section of the light efficiency improving layer 160 among the three
sections corresponding to the red, green and blue organic light
emitting layers 192 may have a different sized area. That is, each
of the three sections of the light efficiency improving layer 160
corresponding to the three colors may have three different
thicknesses or areas from those of the other one portion or two
portions. Alternative exemplary embodiments include configurations
wherein only one or two of the three sections of the light
efficiency improving layer 160 have different thicknesses or areas
from those of the other portions.
[0098] FIG. 7 is a cross-sectional view of fifth exemplary
embodiment of an OLED display according to the present invention.
The fifth exemplary embodiment of an OLED is top-emission type
display as has been described above. A light efficiency improving
layer 160 may be disposed on a common electrode 200 between walls
180 similar to the third exemplary embodiment. Similar to the
fourth exemplary embodiment, an organic light emitting layer 192 in
the OLED emits white light. Therefore, a color filter layer 210 is
formed on the light efficiency improving layer 160. The fifth
exemplary embodiment of an OLED display has a different
configuration from the fourth exemplary embodiment, but uses
substantially the same driving and image forming methods as the
fourth exemplary embodiment due to the fifth exemplary embodiments
requirement of a color filter to display colors.
[0099] FIG. 8 is a cross-sectional view of a sixth exemplary
embodiment of an OLED display according to the present invention. A
light efficiency improving layer 160 is disposed between an organic
passivation layer 153 and an inorganic passivation layer 151 and
includes multiple layers. That is the light efficiency improving
layer 160 includes a first inorganic layer 161a, a second inorganic
layer 163a, a first inorganic layer 161b and a second inorganic
layer 163b which are sequentially formed on the inorganic
passivation layer 151. In one exemplary embodiment the light
efficiency improving layer 160 includes at least one layer which
includes silicon oxide.
[0100] Although a few exemplary embodiments of the present
invention have been shown and described, it will be appreciated by
those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the
invention, the scope of which is defined in the appended claims and
their equivalents.
* * * * *